Method of cleaning disk drive recording head

ABSTRACT

A magnetic disk for self-cleaning a disk drive recording head communicating with a surface of the magnetic disk. The magnetic disk contains an abrasive cleaning zone of a designated width located at an outer periphery on the surface of the magnetic disk. When a recording head periodically passes over and contacts the abrasive surface of the cleaning zone, particles or other contaminants adhered to the recording head are mechanically removed by the relative motion between the rotating disk and the recording head. The recording head may then be returned to a landing zone on the disk, if the cleaning takes place at the end of a stop cycle, or the recording head may be returned to a track in a data zone on the disk if the cleaning takes place during normal disk drive operations.

CROSS REFERENCE TO RELATED APPLICATIONS

This is a divisional application of application Ser. No. 08/856,937,filed May 15, 1997 pending.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention generally relates to a self-cleaning system for adisk drive recording head, and more particularly, to a cleaning zonehaving an abrasive surface that is located on the disk surface tomechanically clean the recording head as it passes over the cleaningzone.

2. Description of the Related Art

Computer disk drive technology evolution has focused on improvements in"areal density", that is, the number of bits of information that can bestored in a given space on a magnetic disk. Over the last decade, themajority of progress has been gained through miniaturization of therecording heads and improving the magnetic efficiency of the write/readelements in the heads, and similar improvements in the magnetic andphysical properties of the disks.

Disk drives contain a plurality of recording heads that "fly" overrotating disks. The magnetic recording efficiency is a function of manyphysical characteristics of the heads and disks, the most significant ofwhich is the spacing between the rotating disk surface 4 and therecording head 2 "pole" elements 6 as shown in FIG. 1. The moststraightforward method for manufacturers to improve areal density hasbeen to reduce the spacing between the head 2 and disk 4, withoutsacrificing the long term reliability of the disk drive.

Across the previous disk drive industry product offerings, head-diskspacing had steadily decreased from several micro-inches to less thantwo micro-inches, until there came a point that further increases inareal density required the head to essentially touch the disk duringflying. A new class of so-called "pseudo-contact" heads were developedin which the rear portion of the head, where the transducer poles 6 arelocated, is in constant contact with the disk surface. Various designcharacteristics were developed to minimize friction and wear between thedisk and head, and such "pseudo-contact" designs have proven to be asreliable over the long-term as the non-contact designs.

A problem arises, however, when foreign material or particles comebetween the head poles and the disk surface, causing a "spacing loss"that affects the magnetic recording process. The types and sources ofthe foreign material are numerous, including; particles generated bymechanical motion of components inside the drive, contaminationintroduced at the time of manufacture, and build-up of excessivelubricant from the disk surface onto the poles of the head. The build-upof contaminants can temporarily increase the spacing between the diskand the recording head, degrading the disk drive performance. Anotherdisadvantage is that contaminants may fall from the recording headduring the stop cycles, creating enough friction between the head, thedisk and the contaminants that a disk drive motor can no longer move therecording head at the commencement of the start cycle.

Great care is taken to remove sources of contamination during assembly,and in the design and fabrication of components used inside the drive toreduce potential sources of particulate generation. But no volumemanufacturing operation can produce completely contamination-freeproduct, and the migration to pseudo-contact recording has significantlyincreased sensitivity to contamination.

In light of the foregoing, there exists a need for a system and methodfor periodically cleaning a recording head as passes over the surface ofthe magnetic disk, without materially degrading the performance of thedisk drive.

SUMMARY OF THE INVENTION

The present invention is directed to an apparatus and method forself-cleaning a disk drive recording head which substantially overcomesone or more of the problems due to the limitations and disadvantages ofthe related art.

In general, the magnetic disk of the present invention employs aself-cleaning zone comprising an abrasive textured surface at the outerperiphery of the disk. When the recording head periodically passes overand contacts the abrasive textured surface in the cleaning zone,particles or other contaminants adhered to the recording head aremechanically removed by the relative motion between the rotating diskand the recording head. The recording head may then be returned to alanding zone on the disk, if the cleaning takes place at the end of astop cycle, or the recording head may be returned to a track and sectorin a data zone on the disk if the cleaning takes place during normaldisk drive operations.

To achieve these and other advantages and in accordance with the purposeof the invention, as embodied and broadly described, the inventionprovides for a magnetic disk for self-cleaning a disk drive recordinghead communicating with a surface of the magnetic disk, the magneticdisk comprising: a landing zone located at an inner periphery on thesurface of the magnetic disk; an abrasive cleaning zone of designatedwidth located at an outer periphery on the surface of the magnetic disk;and a data zone located on the surface of the magnetic disk, between thelanding zone and the abrasive cleaning zone.

In another aspect, the present invention provides for a method ofcleaning a disk drive recording head as it flies over a magnetic diskfor reading data from, or writing data to, the magnetic disk, whereinthe recording head is driven by a disk drive motor, the methodcomprising the steps of: providing a magnetic disk with a landing zoneand a cleaning zone having an abrasive surface; moving the recordinghead to the cleaning zone when a stop motor command is received;maintaining the recording head in the cleaning zone during motorramp-down; cleaning the recording head mechanically as the recordinghead contacts the abrasive surface of the cleaning zone; and moving therecording head to the landing zone before the motor stops.

In still another aspect, the method of cleaning may be utilized duringnormal operations of the recording head. In such a case, the recordinghead is moved back to a track in the data zone, rather than the landingzone, at the end of the cleaning step.

It is to be understood that both the foregoing general description andthe following detailed description are exemplary and explanatory and areintended to provide further explanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other objects, aspects and advantages will be betterunderstood from the following detailed description of a preferredembodiment of the invention with reference to the drawings, thedimensions of which have been distorted and exaggerated to betterillustrate the features of the present invention, where:

FIG. 1 is a side view of a recording head "flying" over a disk;

FIG. 2 is a plan view of magnetic disk having an abrasive cleaning zoneaccording to the present invention;

FIG. 3 is a magnified and more detailed view of the portion "A" of theabrasive cleaning zone of FIG. 2; and

FIG. 4 is a side view showing the rough abrasive surface of the cleaningzone of FIG.2.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

The present invention is directed to a magnetic disk employing acleaning zone having an abrasive textured surface at the outer peripheryof the disk. When the recording head periodically passes over andcontacts the abrasive textured surface in the cleaning zone, foreignparticles or other contaminants adhered to the recording head aremechanically removed by the relative motion between the rotating diskand the recording head.

Reference will be made to FIGS. 2 and 3, which illustrate the magneticdisk having the abrasive cleaning zone according to the presentinvention. The magnetic disk 10 contains a landing zone 12, a data zone14, and a cleaning zone 20. The landing zone 12, at the inner peripheryof the disk, is the portion of the disk where the recording head returnsto after each stop cycle. The data zone 14 typically contains a seriesof tracks and sectors for storing data and extends from the landing zone12 toward the outer periphery of the disk.

The magnetic disk 10 is driven by a motor (not shown) at a given rpm forreading data from, or writing data to, the disk. A recording head 2,similar to that shown in FIG. 1, moves or files above the disk. As therecording head 2 moves over the disk surface, however, foreign materialsor particles can build-up between the head pole elements 6 of therecording head 2 and the disk surface.

Accordingly, the cleaning zone 20 is provided at the outer mostperiphery of the disk. The cleaning zone 20 has an abrasive texturedsurface 21 as shown in FIG. 4. During a cleaning step, particles areremoved from the recording head 2 as it contacts the abrasive texturedsurface 21 due to the relative motion between the rotating disk 10 andthe recording head 2. The mean-to-peak abrasiveness or roughness of thesurface 21 of the cleaning zone 20 should be sufficient to ensure propercleaning, but not cause the recording head 2 to crash. At an upperlimit, therefore, the roughness of the surface 21 of the cleaning zone20 should not exceed the flying height between the recording head 2 andthe magnetic disk 10. Preferably, the roughness of the surface 21 of thecleaning zone 20 may exhibit mean-to-peak ranges from about 40% to about80% of the flying height of the recording head 2. As stated previously,typical flying heights are generally less than two micro-inches.

The abrasive cleaning zone 20 may be prepared by either mechanical orthermal means. Such mechanical means may include, for example, anabrasive slurry deposited on the outer periphery of the magnetic disk.Also, an adhesive tape having an abrasive surface may be applied to theouter periphery of the magnetic disk. One example of a thermal meanswould be the use of a laser to melt certain portions of the outerperiphery of the magnetic disk to create an abrasive textured surface.

The width of the cleaning zone 20, that is, the difference between theinner diameter (ID) and the outer diameter (OD) as shown in FIGS. 2 and3, may vary depending on the width of the recording head. The disk driveindustry generally categorizes the recording heads according to theirwidth, with a so-called 100% recording head being approximately 0.126inches or 126 mils in width. A 50% recording head would thus beapproximately 0.063 inches or 63 mils. Table 1 below lists four typicalrecording heads and their widths.

TABLE 1: Recording Head Types/Widths.

                  TABLE 1                                                         ______________________________________                                        Recording Head Types/Widths                                                   ______________________________________                                        Recording Head Type                                                                          100%     70%     50%    30%                                    Width (mils)   126      89      63     38                                     ______________________________________                                    

The width of the cleaning zone 20 may be less than the recording headwidth, equal to the recording head width, or greater than the recordinghead width. Preferably, the width of the cleaning zone 20 would rangefrom about 0% to about 30% wider than width of the particular recordinghead that is employed. For example, with a 30% recording head, the widthof the cleaning zone would range from about 38 mils to about be about 50mils.

What is important is that the width of the cleaning zone 20 be wideenough to achieve a thorough cleaning of the recording head withoutsacrificing too much time or causing too much of a reduction in the"areal density" of the data zone 14, that is, the number of bits ofinformation that can be stored in a given space on a magnetic disk.Thus, one seeks to achieve a minimum functional width of the cleaningzone 20 while maximizing the data zone 14 to ensure optimum data storageperformance.

The magnetic disk 10 having an abrasive cleaning zone 20 according tothe present invention may be utilized during various operating modes ofthe disk drive system. For example, during a stop cycle, the recordinghead is moved to the cleaning zone 20 when a stop motor command isreceived. The recording head is mechanically cleaned in the cleaningzone 20 during motor ramp-down as the recording head contacts theabrasive textured surface 21. The recording head is then moved to thelanding zone 12 before the motor stops.

The abrasive magnetic disk 10 of the present invention may also beutilized during the normal operating mode of the disk drive system. Insuch a case, the recording head is periodically moved from its presenttrack and sector position in the data zone 14 to the cleaning zone 20while the motor is operating. The periodicity will vary, and isgenerally on the order of every 5 to 10 hours, or whenever a malfunctionoccurs during normal operations. After moving to the cleaning zone 20,the recording head remains in the cleaning zone 20 for a designated timeperiod or designated number of revolutions to ensure sufficientcleaning. Preferably, the recording head would be resident in thecleaning zone 20 for about 10 revolutions of the magnetic disk, althoughapplications involving more or less recording head residence time arecontemplated within the scope of the present invention. What isimportant is that the recording head be sufficiently cleaned withoutundue delay in the functional operation of the disk drive. In the aboveexample, with a disk rotating at 5400 rpm, the recording head would beresident in the cleaning zone for about 0.11 seconds or 110 ms (i.e.,5400 rpm=90 rps=0.011 sec/rev, multiplied by 10 revolutions, equals 0.11seconds). The recording head is then moved back to the prior track andsector in the data zone 14 at the end of the designated period.

The abrasive cleaning disk and method of the present invention may beutilized in many types of disk drive systems, including hard disk drivesor removable hard disk cartridge systems.

While the invention has been described in terms of the embodimentsdescribed above, those skilled in the art will recognize that theinvention can be practiced with modification within the spirit and scopeof the appended claims and their equivalents.

Having thus described my invention, what we claim as new and desire tosecure by letters patent is as follows:
 1. A method of cleaning a diskdrive recording head as it flies over a rotating magnetic disk forreading data from, or writing data to, the magnetic disk, wherein saidrecording head is driven by a disk drive motor, said method comprisingthe steps of:providing the magnetic disk with a landing zone and acleaning zone having an abrasive surface; moving said recording head tothe cleaning zone when a stop motor command is received; maintainingsaid recording head in the cleaning zone during motor ramp-down;cleaning said recording head mechanically as said recording headcontacts said abrasive surface of the cleaning zone; and moving saidrecording head to the landing zone before the motor stops.
 2. The methodof cleaning as in claim 1, wherein during said cleaning step, particlesare removed from the recording head as it contacts the abrasive surfacedue to the relative motion between the rotating disk and the recordinghead.
 3. The method of cleaning as in claim 1, further comprising a stepof forming said abrasive surface by a mechanical means.
 4. The method ofcleaning as in claim 1, further comprising a step of forming saidabrasive surface by a thermal means.